"According to confirmed information, during the two-day special operation three service personnel died and three police officers were wounded," Daghestan's deputy interior minister, Magomed Ismailov, said.

The ministry also said a number of militants had been killed during the operation, although the total figure was unknown due to intense gunfire in the woodland area, where the armed fighters are holed up.

The special operation in Kakashur started after a clash on Wednesday between law enforcement officers and militants. Police then encircled a group of 10 to 15 armed fighters.

The militants are thought to be members of a group aligned to Magomedali Vagabov, who is on a federal and international wanted list for attacks on police officers and terrorist-related crimes.

Sporadic terrorist attacks and militant clashes are common in Daghestan, and in neighboring Chechnya, although the Kremlin has officially ended its military campaign to fight separatists and terrorists there.